IEEE 802.11 is a set of media access control (MAC) and physical layer (PHY) specification for implementing wireless local area network (WLAN) communication in the Wi-Fi (2.4, 3.6, 5, and 60 GHz) frequency bands. The 802.11 family consists of a series of half-duplex over-the-air modulation techniques that use the same basic protocol. The standards and amendments provide the basis for wireless network products using the Wi-Fi frequency bands. Recently, WLAN has seen exponential growth across organizations in many industries.
Orthogonal frequency division multiple access (OFDMA) technology is developed in the cellular network enabling multiple users sharing the same wideband at the same time. Such technology, however, is not developed for the WLAN network. How to adapt the OFDMA technology to the WLAN to enable multiple users sharing the same wideband remains a question. For a normal uplink OFDMA operation, an access point (AP) needs to collect the traffic requests from wireless devices (STAs), arranging and managing the resource used by STAs for the uplink OFDMA transmission. However, only using designated resource for uplink OFDMA may not be efficient.
In OFDM/OFDMA wireless systems, contention-based uplink transmission is commonly used for multiple user equipments (UEs) to transmit uplink data to a serving base station via a shared uplink channel. For example, a UE may request access and acquire ownership of an uplink channel to initiate transmission. Therefore, in WLAN, contention-based random access can also be used for uplink OFDMA operation. For contention-based random access, multiple STAs contend for shared resource.
To improve the efficiency of the WLAN network allowing multiple users to share the same wideband WLAN channel, improvement and enhancement are required for the WLAN network.